Document `anura.daemon.helpers`

[Aversefun]

Currently, the only place anura.daemon.helpers is mentioned is in the example template.init.ajs, and while to me at least it's somewhat self-explanatory, it may not be to everyone. It also only uses need and after and thus it's unclear if there are more provided functions. The current two are also undocumented and there isn't (as far as I know) a clear list of the things you can provide to the need and after functions.

[ProgrammerIn-wonderland]

I believe the template also serves as adequate documentation on its own. It's technically a system library and not a core api, so there would need to be an entire new documentation category for plugin devs, which doesn't exist yet.